Liquid food and beverage preparation machines have been known for a number of years. For example, U.S. Pat. No. 5,943,472 discloses a water circulation system between a water reservoir and a hot water or vapour distribution chamber of an espresso machine. The circulation system includes a valve, metallic heating tube and pump that are connected together and to the reservoir via different silicone hoses, which are joined using clamping collars.
EP 1 646 305 discloses a beverage preparation machine with a heating device that heats circulating water which is then supplied to the inlet of a brewing unit. The brewing unit is arranged to pass heated water to a capsule containing a beverage ingredient for its brewing. The brewing unit has a chamber delimited by a first part and a second part movable relative to the first part and a guide for positioning a capsule in an intermediate position between the first and second parts before moving the first and second parts together from an open to a closed configuration of the brewing unit.
In-line heaters for heating circulating liquid, in particular water are also well known and are for example disclosed in CH 593 044, DE 103 22 034, DE 197 32 414, DE 197 37 694, EP 0 485 211, FR 2 799 630, U.S. Pat. Nos. 4,242,568, 4,595,131, 5,019,690, 5,392,694, 5,943,472, 6,393,967, 6,889,598, 7,286,752, WO 01/54551 and WO 2004/006742.
More particularly, CH 593 044 and U.S. Pat. No. 4,242,568 disclose a coffee machine with an inline thermoblock heater having a metal mass with resistive heating cable cast in the mass and with a duct for the circulation of water to be heated.
EP 0 485 211 discloses a heater for a water heater, shower, washing machine, dishwasher or kettle. The heater includes a vessel for heating liquid, and an electric heating element which is arranged to heat a portion of the vessel. The heating element incorporates a thick-film resistive heating circuit with a thermal fuse included in the thick-film. The document further discloses a triac-type power regulator mounted directly on the heating element that acts as a heat sinker for this triac. Also disclosed is the presence of a thermistor, a temperature sensor, formed on the thick film, a thermal fuse, a flow control valve to continuously adjust the flow rate through the heater, a flow control and a temperature control. These electrical components are connected to a control unit that can be remote or formed as part of the dielectric layer of the thick film at a location close to the inlet pipe where the heater's metal substrate is kept cool by incoming cold water. Similar ideas are disclosed in DE 103 22 034, DE 197 32 414 and DE 197 37 694. In-line tubular heaters for beverage preparation devices are disclosed in WO 01/54551, WO 2004/006742 and U.S. Pat. No. 7,286,752.
U.S. Pat. No. 6,889,598 discloses a beverage device containing a liquid and having an operating apparatus for heating, cooling, agitating, whipping, pumping or frothing the liquid or grinding an ingredient, the operating apparatus being powered via an electronic switch such as a triac that is cooled by being in heat passing relationship with the liquid so as to evacuate the heat produced by the switch to the liquid, in particular via the bottom of a liquid heating tank made of steel or aluminium, and optionally with a radiator.
Moreover, U.S. Pat. No. 5,019,690 discloses a boiling water dispenser that has a resistive heater powered via a triac switch connected via cables to a control module and mounted on the bottom of the dispenser's water reservoir to evacuate heat generated at the triac switch via the water.
U.S. Pat. No. 4,595,131 discloses a beverage preparation machine with a water heating reservoir that is electrically connected to a printed circuit board via a series of cables leading to a thermostatically controlled heater and a thermistor probe in the reservoir. EP 1 610 596 discloses a heat evacuation system for a printed circuit board that includes layers of thermally highly conductive material extending to a thermally conductive bar located at and along an edge of the printed circuit board for dissipation of heat generated by the printed circuit board.
FR 2 799 630 discloses an espresso machine having a cold water reservoir connected to a brewing unit via a pump and a thermoblock. The thermoblock includes a temperature sensor and an electric heater. The temperature sensor and the heater are connected to a printed circuit board with a controller, electric power being passed to the heater via a triac located on the printed circuit board and controlled by the controller.